WO2022059738A1 - Sealing material for display element, cured object obtained therefrom, and display device - Google Patents

Abstract

Provided is a sealing material for display elements that comprises component (A), which is a polymerizable compound, component (B), which is a polymerization initiator, and component (C), which is an antioxidant. The sealing material for display elements gives a cured object having a glass transition temperature of 90°C or higher but lower than 200°C.

Description

Sealants for display elements, cured products thereof, and display devices

The present invention relates to a sealant for a display element, a cured product thereof, and a display device.

In the field of display devices, studies have been made to improve the characteristics of sealants. Hereinafter, an organic EL display device will be described as an example.
Organic EL elements are being used in displays, lighting devices, and the like because they consume less power. Since organic EL elements are easily deteriorated by moisture and oxygen in the atmosphere, they are used by being sealed with various sealing members, and the durability of moisture and oxygen of various sealing members will be improved for practical use. It is desired.

As a method for sealing the organic EL, for example, a method is used in which a resin layer is formed on an organic EL element coated with a first layer of an inorganic material film, and then a second layer of the inorganic material film is coated. ing. Examples of the method of coating with the inorganic material film include a method of forming an inorganic material film made of silicon nitride or silicon oxide by a sputtering method, an electron cyclotron resonance (ECR) plasma CVD method, or the like.

Patent Document 1 (International Publication No. 2018/70488) describes a specific (meth) acrylate as a technique for providing a composition having excellent coatability and low moisture permeability when used for encapsulating an organic EL device. A composition containing a specific amount of the above has been proposed. According to the same document, "When the glass transition temperature of the cured product obtained from the composition is 200 ° C. or higher, an inorganic passion film is formed on the cured product of the composition of the present embodiment by a method such as CVD. , The thermal expansion prevents the occurrence of pinholes due to uneven film formation of the inorganic passivation film, and the reliability of the organic EL element is improved "(paragraph 0081).

Patent Document 2 (Japanese Patent Laid-Open No. 2017-523549) provides a composition for encapsulating an organic light emitting device, which can realize an organic barrier layer having excellent plasma resistance and improve the reliability of the organic light emitting device. The purpose is to do.

International Publication No. 2018/070488 Special Table 2017-523549 Publication No.

When the present inventors have studied the techniques described in the above patent documents, it is expected that patent document 1 may not be suitable for devices that require flexibility because the glass transition temperature of the cured product is high. In that respect, there was room for improvement.

Further, in the technique described in Patent Document 2, since the encapsulating composition contains a silicon-based di (meth) acrylate having a specific skeleton, it is suitable for a device having a high glass transition temperature and also requiring flexibility. There was room for improvement in that it was expected to be absent.

The present invention provides a sealant for a display element capable of forming a resin layer having excellent plasma resistance and high flexibility.

According to the present invention, a sealant for a display element, a cured product, and a display device shown below are provided.
[1] The following components (A) to (C):
A sealant for a display device containing (A) a polymerizable compound (B) a polymerization initiator (C) an antioxidant.
A sealant for a display element, wherein the glass transition temperature of the cured product of the sealant for the display element is 90 ° C. or higher and lower than 200 ° C.
[2] The sealant for a display device according to [1], wherein the component (C) is a hindered phenol compound.
[3] The component (C) is at least one of dibutylhydroxytoluene and pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], [1] or [ 2] The sealant for a display element according to the above.
[4] The sealant for a display device according to any one of [1] to [3], wherein the component (A) is a compound containing a (meth) acryloyl group.
[5] The sealing agent for a display element according to any one of [1] to [4], which is used for sealing an organic EL display element.
[6] A cured product obtained by curing the sealant for a display element according to any one of [1] to [5].
[7] With the board
Display elements arranged on the substrate and
The sealing layer that covers the display element and
Including
A display device in which the sealing layer is made of a cured product of the sealing agent for a display element according to any one of [1] to [5].

According to the present invention, it is possible to provide a sealing agent for a display element capable of forming a resin layer having excellent plasma resistance and high flexibility.

It is sectional drawing which shows the structural example of the organic EL display device in Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, similar components are designated by a common reference numeral, and the description thereof will be omitted as appropriate. Further, in the present embodiment, one kind may be used for each component, or two or more kinds may be used in combination. Further, "-" representing a numerical range indicates the above and below, and includes both an upper limit value and a lower limit value.

(Seal for display elements)
In the present embodiment, the sealing agent for a display element (hereinafter, also simply referred to as “sealing agent” as appropriate) is a composition used for sealing an element, and the following components (A) to (C). The glass transition temperature of the cured product is 90 ° C. or higher and lower than 200 ° C.
(A) Polymerizable Compound (B) Polymerization Initiator (C) Hindered Amine First, the constituent components of the encapsulant will be described with specific examples.

(Ingredient (A))
The component (A) is a polymerizable compound. The component (A) may be a compound having a polymerizable functional group, and is preferably a compound having a radically polymerizable functional group.

Specific examples of the radically polymerizable functional group include one or more groups selected from the group consisting of (meth) acryloyl group and vinyl group. From the viewpoint of improving curability, the component (A) is preferably a compound containing a (meth) acryloyl group.
Here, in the present specification, the (meth) acryloyl group means at least one of an acryloyl group and a methacryloyl group. Further, (meth) acrylic means at least one of acrylic and methacrylic. Further, the (meth) acrylate means at least one of acrylate and methacrylate.

Specific examples of the (meth) acrylic compound having a (meth) acryloyl group include a mono (meth) acrylic compound, a di (meth) acrylic compound, and a trifunctional or higher functional (meth) acrylic compound.

Specific examples of the mono (meth) acrylic compound include isobornyl (meth) acrylate, dicyclopentanyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, and 4-tershalbutylcyclohexyl (meth) acrylate. , Dicyclopentenyloxyethyl (meth) acrylicate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) ) Acrylate, Isooctyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, methoxytriethylene glycol (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethoxyethyl (meth) Acrylate, Butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxydixylethyl (meth) acrylate, ethyldiglycol (meth) acrylate, cyclic trimethylolpropaneformal mono (meth) acrylate, imide (meth) acrylate, Isoamyl (meth) acrylate, ethoxylated succinic acid (meth) acrylate, trifluoroethyl (meth) acrylate, ω-carboxypolycaprolactone mono (meth) acrylate, cyclohexyl (meth) acrylate, 2- (2-ethoxyethoxy) ethyl ( Meta) acrylate, stearyl (meth) acrylate, diethylene glycol monobutyl ether (meth) acrylate, lauryl (meth) acrylate, isodecyl (meth) acrylate, isooctyl (meth) acrylate, octyl / decyl (meth) acrylate, tridecyl (meth) acrylate, Caprolactone (meth) acrylate, ethoxylated (4) nonylphenol (meth) acrylate, methoxypolyethylene glycol (350) mono (meth) acrylate, methoxypolyethylene glycol (550) mono (meth) acrylate, phenoxyethyl (meth) acrylate, cyclohexyl ( Meta) acrylate, tetrahydrofurfuryl (meth) acrylate, benzyl (meth) acrylate, methylphenoxyethyl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, tribromophenyl (meth) ) Acrylate, ethoxylated tribromophenyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate ethylene oxide adduct, 2-phenoxyethyl (meth) acrylate propylene oxide adduct, Examples thereof include phenoxydiethylene glycol (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 3-methacryloyloxymethylcyclohexene oxide, and 3- (meth) acryloyloxymethylcyclohexene oxide.

Specific examples of the di (meth) acrylic compound include di (meth) acrylate of diol and di (meth) acrylate of (poly) alkylene glycol, and more specifically, 1,6-hexanediol diacrylate (for example). A-HD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,9-nonanediol diacrylate (for example, A-NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd .; light acrylate 1,9ND-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,10-decanediol diacrylate (for example, A-DOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), neopentyl glycol diacrylate (for example, A-NPG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd .; Light Acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd.) , Ethylene Glycol Diacrylate (eg SR206NS, manufactured by Alchema), Polyethylene Glycol Diacrylate (eg A-400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), Polypropylene Glycol Diacrylate (eg APG-400, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) , Tricyclodecanedimethanol diacrylate (dimethylol-tricyclodecanediacrylate) (for example, A-DCP, manufactured by Shin-Nakamura Chemical Industry Co., Ltd .; light acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd.), 1,3-butanediol. Dimethacrylate (eg BG, manufactured by Shin-Nakamura Chemical Industry), 1,4-butanediol dimethacrylate (eg BD, manufactured by Shin-Nakamura Chemical Industry), 1,6-hexanediol dimethacrylate (eg HD-N, manufactured by Shin-Nakamura) Chemical Industry Co., Ltd.), 1,9-Nonandiol dimethacrylate (for example, NOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), 1,10-decanediol dimethacrylate (for example, DOD-N, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), Examples thereof include 1,12-dodecanediol diacrylate (for example, SR262, manufactured by Sartmer) and neopentyl glycol dimethacrylate (for example, NPG, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.).

Specific examples of trifunctional or higher functional polyfunctional (meth) acrylic compounds include trimethylolpropane triacrylate (for example, A-TMPT, manufactured by Shin-Nakamura Chemical Industry Co., Ltd .; light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.), and ethoxylated trimethylol. Propanetriacrylate (eg A-TMPT-EO, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), ethoxylated glycerin triacrylate (eg A-GLY-6E, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), propoxylated glycerin triacrylate (eg A-GLY) -3P, manufactured by Shin Nakamura Chemical Industry Co., Ltd.) and other trifunctional (meth) acrylic compounds;
Pentaerythritol tetraacrylate (eg A-TMMT, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), ethoxylated pentaerythritol tetraacrylate (eg ATM-4E, manufactured by Shin Nakamura Chemical Industry Co., Ltd.), ditrimethylolpropane tetraacrylate (eg AD-TMP-L) , Shin Nakamura Chemical Industry Co., Ltd.) and other tetrafunctional (meth) acrylic compounds;
Five-functional (meth) acrylate compounds such as dipentaerythritol pentaacrylate (eg M-402, manufactured by Toagosei); and six-functional (meth) acrylics such as dipentaerythritol hexaacrylate (eg GM66G0H, manufactured by Kokusei Kagaku). Examples include compounds.

From the viewpoint of improving the durability of a display device, for example, an organic EL display device during long-term use, the component (A) preferably contains a (meth) acrylic compound having two or more (meth) acryloyl groups in one molecule. , More preferably a di (meth) acrylic compound, and even more preferably a di (meth) acrylic compound having an alicyclic structure and a di (meth) acrylic compound having a chain structure.

The di (meth) acrylic compound having an alicyclic structure has an alicyclic hydrocarbon structure in the molecular structure, and the number of carbon atoms in the alicyclic hydrocarbon structure is preferably 4 or more from the viewpoint of improving heat resistance. Yes, more preferably 5 or more, still more preferably 6 or more, still preferably 14 or less, more preferably 12 or less, still more preferably 10 or less.
The alicyclic hydrocarbon structure may be a saturated hydrocarbon structure or an unsaturated hydrocarbon structure. From the viewpoint of improving heat resistance, the alicyclic hydrocarbon structure is preferably a saturated hydrocarbon structure.

Further, the alicyclic hydrocarbon structure may be a monocyclic hydrocarbon structure, a fused ring hydrocarbon structure, or a polycyclic hydrocarbon structure having a bridge ring hydrocarbon group structure. The di (meth) acrylic compound having an alicyclic structure may contain a group containing these alicyclic hydrocarbon structures in the molecular structure, and preferably contains a divalent group containing an alicyclic hydrocarbon structure.
Specific examples of the monocyclic hydrocarbon group include a group having a cycloalkane structure such as a cyclohexylene group and a cyclohexyl group; and a group having a cycloalkene skeleton such as a cyclodecatoriendiyl group and a cyclodecatorien group.
Specific examples of the polycyclic hydrocarbon group include a group having a dicyclopentadiene skeleton such as a tricyclodecandyl group, a dicyclopentanyl group, and a dicyclopentenyl group; a norbornanediyl group, an isobornanediyl group, and a norbornyl group. Groups having a norbornane skeleton such as an isobornyl group; groups having an adamantane skeleton such as an adamantane diyl group and an adamantane group can be mentioned.

The cyclic hydrocarbon group in the di (meth) acrylic compound having an alicyclic structure is preferably a group having a dicyclopentadiene skeleton from the viewpoint of improving plasma resistance and low moisture permeability.
Further, the di (meth) acrylic compound having an alicyclic structure contains tricyclodecanedimethanol di (meth) acrylate from the viewpoint of improving plasma resistance and low moisture permeability, and more preferably tricyclodecanedimethanol. Di (meth) acrylate.

The content of the di (meth) acrylic compound having an alicyclic structure in the encapsulant is preferably 5 parts by mass or more, and more preferably 10 parts by mass with respect to 100 parts by mass of the polymerizable compound from the viewpoint of improving heat resistance. By mass or more, more preferably 15 parts by mass or more, even more preferably 20 parts by mass or more, even more preferably 25 parts by mass or more, still more preferably 30 parts by mass or more.
Further, from the viewpoint of making the inkjet coatability more preferable, the content of the di (meth) acrylic compound having an alicyclic structure in the encapsulant is preferably 60 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. It is more preferably 58 parts by mass or less, further preferably 56 parts by mass or less, and even more preferably 50 parts by mass or less.

The di (meth) acrylic compound having a chain structure is specifically a (meth) acrylate having a chain structure in its molecular structure and having two or more (meth) acrylic groups, from the viewpoint of improving strength. Therefore, it is preferably a (meth) acrylate having two (meth) acrylic groups.

In the di (meth) acrylic compound having a chain structure, the chain structure may be a linear structure or a structure having branches.
The chain structure preferably contains a divalent hydrocarbon group having a straight chain or a branched chain from the viewpoint of making the inkjet coatability more preferable. The number of carbon atoms of the divalent hydrocarbon group is, for example, 1 or more, preferably 2 or more, and more preferably 4 or more, from the viewpoint of accessibility of the monomer. Further, from the viewpoint of improving heat resistance, the number of carbon atoms of the divalent hydrocarbon group is preferably 20 or less, more preferably 14 or less.

Specific examples of the di (meth) acrylic compound having a chain structure include di (meth) acrylate of alkanediol and di (meth) acrylate of (poly) alkylene glycol, and specific examples of the di (meth) acrylic compound are preferable. As an example, among the above-mentioned compounds, one or more compounds selected from the group consisting of di (meth) acrylate of alcandiol and di (meth) acrylate of (poly) alkylene glycol.
From the viewpoint of improving plasma resistance, improving coating stability in the inkjet method, and improving the balance between the effects of low dielectric constant, the di (meth) acrylic compound having a chain structure is a 1,9-nonanediol di (meth) acrylate. And one or more (meth) acrylates selected from the group consisting of neopentyl glycol di (meth) acrylates.

The content of the di (meth) acrylic compound having a chain structure in the encapsulant is preferably 5 parts by mass or more with respect to 100 parts by mass of the polymerizable compound from the viewpoint of making the inkjet coating property more preferable. , More preferably 10 parts by mass or more, still more preferably 15 parts by mass or more, still more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more.
Further, from the viewpoint of improving plasma resistance, the content of the di (meth) acrylic compound having a chain structure in the encapsulant is preferably 60 parts by mass or less with respect to 100 parts by mass of the polymerizable compound. It is preferably 58 parts by mass or less, more preferably 56 parts by mass or less, and even more preferably 50 parts by mass or less.

The content of the component (A) in the encapsulant is preferably 70% by mass or more, more preferably 80% by mass or more, based on the total composition of the encapsulant, from the viewpoint of improving the strength of the cured product. It is more preferably 85% by mass or more, still more preferably 90% by mass or more, and even more preferably 93% by mass or more.
Further, from the viewpoint of improving the weather resistance of the encapsulant, the content of the component (A) in the encapsulant is preferably 99.9% by mass or less with respect to the total composition of the encapsulant, which is more preferable. Is 99.5% by mass or less, more preferably 99% by mass or less, and even more preferably 98% by mass or less.

(Component (B))
The component (B) is a polymerization initiator. From the viewpoint of stably forming a cured product at a low temperature, the component (B) is preferably a photopolymerization initiator which is a compound that generates radicals or acids by irradiation with ultraviolet rays or visible light. Examples of the photopolymerization initiator include an acylphosphine oxide-based initiator, an oxyphenylacetic acid ester-based initiator, a benzoylformic acid-based initiator, a hydroxyphenylketone-based initiator, and the like.

Specific examples of the photopolymerization initiator include benzophenone, Michler's ketone, 4,4'-bis (diethylamino) benzophenone, xanthone, thioxanthone, isopropylxanthone, 2,4-diethylthioxanthone, 2-ethylanthraquinone, acetophenone, and 2-hydroxy-. 2-Methyl-4'-isopropylpropiophenone, isopropylbenzoin ether, isobutylbenzoin ether, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, camphorquinone, benzanthron, 4-dimethylaminobenzo Ethyl acid, isoamyl 4-dimethylaminobenzoate, 4,4'-di (t-butylperoxycarbonyl) benzophenone, 3,4,4'-tri (t-butylperoxycarbonyl) benzophenone, 3,3', 4, 4'-Tetra (t-butylperoxycarbonyl) benzophenone, 3,3', 4,4'-tetra (t-hexylperoxycarbonyl) benzophenone, 3,3'-di (methoxycarbonyl) -4,4'-di (T-butylperoxycarbonyl) benzophenone, 3,4'-di (methoxycarbonyl) -4,3'-di (t-butylperoxycarbonyl) benzophenone, 4,4'-di (methoxycarbonyl) -3,3' -Di (t-butylperoxycarbonyl) benzophenone, 2- (4'-methoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (3', 4'-dimethoxystyryl) -4, 6-bis (trichloromethyl) -s-triazine, 2- (2', 4'-dimethoxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 2- (2'-methoxystyryl) -4 , 6-bis (trichloromethyl) -s-triazine, 2- (4'-pentyloxystyryl) -4,6-bis (trichloromethyl) -s-triazine, 4- [p-N, N-di (ethoxy) Carbonylmethyl)] -2,6-di (trichloromethyl) -s-triazine, 1,3-bis (trichloromethyl) -5- (2'-chlorophenyl) -s-triazine, 1,3-bis (trichloromethyl) )-5- (4'-methoxyphenyl) -s-triazine, 2- (p-dimethylaminostyryl) benzoxazole, 2- (p-dimethylaminostyryl) benzthiazole, 2-mercaptobenzothiazole, 3,3' -Mallynbis (7-Die) (Thylaminocoumarin), 2- (o-chlorophenyl) -4,4', 5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis (2-chlorophenyl) -4,4' , 5,5'-tetrakis (4-ethoxycarbonylphenyl) -1,2'-biimidazole, 2,2'-bis (2,4-dichlorophenyl) -4,4', 5,5'-tetraphenyl- 1,2'-biimidazole, 2,2'-bis (2,4-dibromophenyl) -4,4', 5,5'-tetraphenyl-1,2'-biimidazole, 2,2'-bis (2,4,6-trichlorophenyl) -4,4', 5,5'-tetraphenyl-1,2'-biimidazole, 3- (2-methyl-2-dimethylaminopropionyl) carbazole, 3,6 -Bis (2-methyl-2-morpholinopropionyl) -9-n-dodecylcarbazole, bis (η5-2,4-cyclopentadiene-1-yl) -bis (2,6-difluoro-3- (1H-) Pyrol-1-yl) -Phenyl) Titanium, 1-Hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenyl-1-propanol, 1- [4- (2-hydroxyethoxy) -phenyl] -2 -Hydroxy-2-methyl-1-propanone, 2-hydroxy-1-{4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-1-propanone, 2- Methyl-1- [4- (Methylthio) Phenyl] -2-morpholino-1-propanol, 2- (dimethylamino) -1- (4-morpholinophenyl) -2-benzyl-1-butanone, 2- (dimethylamino) )-2-[(4-Methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, oxy-phenyl-acetate 2- [2-oxo-2-phenyl-acetoxy-ethoxy ] -Ethyl ester, oxy-phenyl-acetic acid 2- [2-hydroxy-ethoxy] -ethyl ester, methyl benzoyllate, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2,4,6-trimethyl Phenylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphinic acid ester, 1- [4- (phenylthio) phenyl] -1,2-octanedione 2- (O-benzoyloxime)], 1- [ 9-Ethyl-6- (2-Methylbenzoyl) -9H-ka Lubazole-3-yl] -etanone-1- (O-acetyloxime) and the like can be mentioned.

Among these, from the viewpoint of improving curability, the photopolymerization initiator is preferably 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenyl-1-propanol, 1- [4- ( 2-Hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propanone, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl}- 2-Methyl-1-propanol, 2,2-dimethoxy-2-phenylacetophenone, oxy-phenyl-acetic acid 2- [2-oxo-2-phenyl-acetoxy-ethoxy] -ethyl ester, oxy-phenyl-acetic acid 2- [2-Hydroxy-ethoxy] -ethyl ester, methyl benzoylate, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenylphosphinoxide (TPO) and 2, One or more compounds selected from the group consisting of 4,6-trimethylbenzoyldiphenylphosphinic acid ester.

Commercially available photopolymerization initiators include Irgacure 184, Irgacure 651, Irgacure 127, Irgacure 1173, Irgacure 500, Irgacure 2959, Irgacure 754, IrgacureMBF, IrgacureMBF, IrgacureTPO (above, BASF), etc.

The content of the component (B) in the encapsulant is preferably 0.1% by mass or more, more preferably 0.5% by mass, based on the total composition of the encapsulant, from the viewpoint of improving the curability. As mentioned above, it is more preferably 1% by mass or more, and even more preferably 2% by mass or more.
Further, from the viewpoint of suppressing the coloring of the encapsulant, the content of the component (B) in the encapsulant is preferably 10% by mass or less, more preferably 8% by mass, based on the total composition of the encapsulant. % Or less, more preferably 6% by mass or less, still more preferably 5% by mass or less.

(Component (C))
The component (C) is an antioxidant. Specific examples of the antioxidant include a hindered phenolic antioxidant and a phosphorus-based antioxidant. Among them, a hindered phenolic antioxidant is preferable, and more specifically, a hindered phenol compound is preferable from the viewpoint of improving plasma resistance. A hindered phenolic antioxidant is a substance having a phenolic hydroxyl group that receives a radical generated by a reaction with oxygen and changes it into a stable phenoxy radical.

Examples of the hindered phenol compound include dibutylhydroxytoluene, that is, 2,6-bis (1,1-dimethylethyl) -4-methylphenol (BHT manufactured by Wako Pure Chemical Industries, Ltd.), 3,5-di-tert-butyl-4. -Hydrhydroxytoluene, pentaerythritol-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (BASF, trade name IRGANOX1010; ADEKA, AO-60), octadecyl-3 -(3,5-Di-tert-butyl-4-hydroxyphenyl) propionate (manufactured by BASF, trade name IRGANOX1076) and the like can be mentioned.

Phosphorus-based antioxidants include 2,2-methylenebis (4,6-dit-butylphenyl) octylphosphite (manufactured by ADEKA; trade name: ADEKA STAB HP-10), tris (2,4-dit-). Phosphite esters such as butylphenyl) phosphite (manufactured by BASF; trade name: IRGAFOS168) can be mentioned.

From the viewpoint of improving the flexibility and plasma resistance of the encapsulating material, the component (C) is dibutylhydroxytoluene and pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. At least one of.

The content of the component (C) in the encapsulant is preferably 0.01% by mass or more, more preferably 0, based on the total composition of the encapsulant, from the viewpoint of improving the flexibility of the encapsulant. .1% by mass or more, more preferably 0.2% by mass or more, still more preferably 0.3% by mass or more.
Further, from the viewpoint of improving the curability of the encapsulant, the content of the component (C) in the encapsulant is preferably 2% by mass or less, more preferably 1% by mass, based on the total composition of the encapsulant. % Or less, more preferably 0.8% by mass or less, still more preferably 0.6% by mass or less.

Regarding the amount ratio of the component (C) to the component (A), from the viewpoint of improving the flexibility of the encapsulating material, the content of the component (C) in the encapsulant is 100 parts by mass of the component (A). On the other hand, it is preferably 0.01 part by mass or more, more preferably 0.1 part by mass or more, still more preferably 0.2 part by mass or more, still more preferably 0.3 part by mass or more.
Further, from the viewpoint of improving the curability of the encapsulating material, the content of the component (C) in the encapsulant is preferably 2 parts by mass or less with respect to 100 parts by mass of the component (A), more preferably. It is 1 part by mass or less, more preferably 0.8 part by mass or less, still more preferably 0.6 part by mass or less.

In the present embodiment, the encapsulant may be composed of the components (A) to (C), or may contain components other than the components (A) to (C). For example, the encapsulant may further contain component (D): a polymerization inhibitor.

(Component (D))
The component (D) is a polymerization inhibitor. Specific examples of the component (D) include 2,2,6,6-tetramethylpiperidine-1-oxyl (free radical) and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical). Radical), 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical), 4-partamide-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical), 4-Acetamide-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical), 4-carboxy-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical), 4- Examples thereof include methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical) 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (free radical).

The content of the component (D) in the encapsulant is preferable with respect to the entire composition of the encapsulant from the viewpoint of improving plasma resistance and suppressing damage to the element to which the encapsulant is applied. Is 0.001% by mass or more, more preferably 0.01% by mass or more, still more preferably 0.005% by mass or more.
Further, from the viewpoint of improving the curability of the encapsulant, the content of the component (D) in the encapsulant is preferably 1% by mass or less, more preferably 0. It is 75% by mass or less, more preferably 0.5% by mass or less.

(Other ingredients)
Specific examples of the components other than the components (A) to (C) include, in addition to the above-mentioned component (D), an antistatic agent, a filler, a curing accelerator, a plasticizer, a surfactant, a heat stabilizer, a flame retardant, and the like. Included is one or more additives selected from the group consisting of antistatic agents, defoaming agents, leveling agents and UV absorbers.

Next, the characteristics of the encapsulant will be described.
The glass transition temperature (Tg) of the cured product of the encapsulant is 90 ° C. or higher, preferably 110 ° C. or higher, and more preferably 130 ° C. or higher from the viewpoint of improving the heat resistance of the encapsulant.
Further, from the viewpoint of improving the flexibility, the Tg of the cured product of the encapsulant is less than 200 ° C., preferably 190 ° C. or lower, more preferably 180 ° C. or lower.

Here, the glass transition temperature (Tg) is measured by the following procedure.
The cured product of the encapsulant uses a 100 μm thick Teflon (registered trademark) sheet as a mold, sandwiches the uncured encapsulant between polyethylene terephthalate (PET) films, and has an illuminance of 1000 mW / LED with a UV-LED having a wavelength of 395 nm. It is obtained by curing under the conditions of cm ² and an integrated light amount of 1500 mJ / cm ² .
The obtained cured product is cut into a size of 10 mm in width × 40 mm in length with a cutter.
Then, using the dynamic viscoelasticity measuring device "DMS6100" (manufactured by Seiko Instruments Inc.), the cured product cut out in the atmosphere is heated at a temperature of 5 ° C./min from room temperature to 250 ° C. while applying a frequency of 1 Hz. , Tan δ is measured, and the temperature of the peak top of tan δ is defined as Tg of the cured product.

In the present embodiment, the encapsulant having a Tg in a specific range can be obtained, for example, by appropriately selecting the components and the blending ratio contained in the resin composition and adjusting the production conditions.

The properties of the encapsulant are not limited, and the encapsulant is suitable from the viewpoint of improving the flexibility and plasma resistance of the encapsulating material and being suitable for forming a cured material by a coating method such as an inkjet method. It is preferably liquid.

Further, in the embodiment, from the viewpoint of stably forming a sealing material such as a resin film, the sealing agent is preferably a sealing agent used for coating, and more preferably a sealing used for coating by an inkjet method. It is a stop agent.

The viscosity of the encapsulant measured at 25 ° C. and 20 rpm using an E-type viscometer is preferably 5 mPa · s or more, more preferably 8 mPa · s or more, still more preferably, from the viewpoint of improving the inkjet ejection property. Is 10 mPa · s or more.
Further, from the viewpoint of improving the inkjet ejection property, the viscosity of the encapsulant is preferably 30 mPa · s or less, more preferably 28.5 mPa · s or less, and further preferably 27 mPa · s or less.

The dielectric constant of the cured product of the sealant is preferably 4.0 or less, more preferably 3.8 or less, still more preferably 3.6 or less, from the viewpoint of improving the sealing characteristics of the sealant. ..
Further, the dielectric constant of the cured product of the encapsulant can be, for example, 1.0 or more.
Here, the dielectric constant of the cured product of the encapsulant is the cured product obtained by curing the curable composition under the conditions of an illuminance of 1000 mW / cm ² and an integrated light intensity of 1500 mJ / cm ² with a UV-LED having a wavelength of 395 nm. Permittivity measured at a frequency of 100 kHz.

Next, a method for producing a sealant will be described.
The method for producing the encapsulant is not limited, and includes, for example, mixing the components (A) to (C) and other components as appropriate, for example, various additives to be added as needed. As a method of mixing each component, for example, various known kneaders such as a planetary stirrer, a homodisper, a universal mixer, a Banbury mixer, a kneader, two rolls, three rolls, and an extruder are used alone or in combination. Examples thereof include a method of uniformly kneading under conditions such as normal pressure, reduced pressure, pressure, and an inert gas stream under normal temperature or heating.

Further, a sealing material can be formed by using the obtained sealing agent. For example, a sealant may be applied onto the substrate and dried. For coating, a known method such as an inkjet method, screen printing, or dispenser coating can be used. Further, the drying can be performed, for example, by heating to a temperature at which the component (A) does not polymerize. The shape of the obtained encapsulating material is not limited and may be, for example, a film or a layer.

The encapsulating material is, for example, a cured product obtained by curing the encapsulant in the present embodiment, and more specifically, a photocured product of the encapsulant.
Examples of the method of photocuring the encapsulant include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, excima lasers, chemical lamps, black light lamps, microwave-excited mercury lamps, metal halide lamps, sodium lamps, and halogen lamps. , A method of curing by irradiating light using a light source such as a xenon lamp, an LED lamp, a fluorescent lamp, sunlight, or an electron beam irradiator.

In the present embodiment, the encapsulant contains the components (A) to (C) in combination and Tg is in a specific range. Therefore, by using such an encapsulant, plasma resistance is excellent and flexibility is increased. A high resin layer can be formed. By using such a resin layer as a sealing material, a display device having excellent reliability can be obtained.

Further, the encapsulant obtained in the present embodiment is suitably used for encapsulating a display element, preferably an organic EL display element, for example. According to the present embodiment, a sealing agent capable of forming a resin layer having excellent plasma resistance and high flexibility can be obtained. Therefore, for example, damage to a display element in a manufacturing process of a display device can be effectively suppressed. This makes it possible to improve the manufacturing stability of the display device.
Hereinafter, a configuration example of the display device will be given by taking an organic EL display device as an example.

(Organic EL display device)
In the present embodiment, the organic EL display device has a layer made of a cured product of a sealing agent. By protecting the organic EL element with a resin layer obtained by curing the encapsulant of the present embodiment, the infiltration of water into the organic EL element is sufficiently prevented, and the performance and durability of the organic EL element are improved. Can be kept high.

The organic EL display device may have a top emission structure or a bottom emission structure.
The organic EL element is arranged on a substrate and is pre-coated with an inorganic material film so as to cover the region containing the organic EL element before being protected by the resin layer obtained by curing the encapsulant in the present embodiment. It is preferable that it is.

FIG. 1 is a cross-sectional view showing a configuration example of an organic EL display device according to the present embodiment. The display device 100 shown in FIG. 1 is an organic EL display device, which comprises a substrate (base material layer 50), an organic EL element (light emitting element 10) arranged on the base material layer 50, and a light emitting element 10. A sealing layer 22 (which may be an overcoat layer 22 or a barrier layer 22) to be coated is included. Then, for example, the sealing layer 22 is composed of a cured product of the sealing agent in the present embodiment.
Further, in FIG. 1, the display device 100 has a barrier layer 21 (may be a touch panel layer 21 or a surface protection layer 21) and a sealing layer 22 (which may be a touch panel layer 21 or a surface protection layer 21) as layers located on the observation side of the light emitting element 10. It has an overcoat layer 22 or a barrier layer 22), a flattening layer 23 (may be a sealing layer 23), and a barrier layer 24. The flattening layer 23 is provided on the base material layer 50 so as to cover the light emitting element 10, and the barrier layer 24 is provided on the surface of the flattening layer 23. The sealing layer 22 is provided on the base material layer 50 so as to cover the flattening layer 23 and the barrier layer 24. Further, a barrier layer 21 is provided on the sealing layer 22.

The material of the base material layer 50 is not limited, and various materials such as a glass substrate, a silicon substrate, and a plastic substrate can be used. A TFT substrate having a plurality of TFTs (thin film transistors) and a flattening layer on the substrate can also be used.

Examples of the inorganic material constituting the barrier layer 24, that is, the above-mentioned inorganic material film, include silicon nitride (SiN _x ), silicon oxide (SiO _x ), aluminum oxide (Al ₂ O ₃ ), and the like. The inorganic material film may be a single layer or a laminated body of a plurality of types of layers.
Examples of the method of covering the light emitting element 10 with the inorganic material film include a sputtering method and an electron cyclotron resonance (ECR) plasma CVD method when the inorganic material film is made of silicon nitride or silicon oxide.

Of these, the sputtering method can be carried out under the conditions of room temperature, electric power of 50 to 1000 W, and pressure of 0.001 to 0.1 Torr, for example, using a single gas such as argon or nitrogen as a carrier gas or a mixed gas.
Further, in the ECR plasma CVD method, for example, a mixed gas of SiH ₄ and O ₂ or a mixed gas of SiH ₄ and N ₂ is used, and the temperature is 30 ° C to 100 ° C, the pressure is 10 mTorr to 1Torr, the frequency is 2.45 GHz, and the power is increased. It can be performed under the condition of 10 to 1000 W.

As a method of protecting the light emitting element 10 with a resin layer obtained by curing the sealing agent of the present embodiment, for example, a sealing layer 22, for example, a method of applying a sealing agent on the light emitting element 10 and curing the light emitting element 10. And so on. As a coating method, it is preferable to use an inkjet method.
The thickness of the resin layer is not limited, but is, for example, 0.1 to 50 μm, preferably 1 to 20 μm from the viewpoint of improving the sealing performance and the flexible performance.

Further, in the display device 100, in order to enhance the effect of protecting the light emitting element 10 from moisture and oxygen in the atmosphere, it is preferable to further laminate an inorganic material film (barrier layer 24) on the above-mentioned resin layer. The inorganic material and the forming method for forming the inorganic material film laminated on the resin layer are the same as those for the inorganic material film covering the light emitting element 10 described above.
The thickness of the inorganic material film formed on the resin layer is not limited, but is, for example, 0.01 to 10 μm, preferably 0.1 to 5 μm from the viewpoint of improving the sealing performance.

In the display device 100, the barrier layer 24 and the sealing layer 22 are provided on the light emitting element 10, and the sealing layer 22 is composed of a resin layer obtained by curing the sealing agent in the present embodiment. Therefore, it is possible to obtain a display device 100 having excellent reliability. Specifically, damage to the barrier layer 24 can be suppressed even when the plasma treatment step is performed when the barrier layer 24 is formed on the sealing layer 22, and for example, a SiN _x film. It is possible to suppress the generation of pinholes in the barrier layer 24. Therefore, for example, when the product is stored in a temperature range of about 85 ° C., outgas is less likely to be generated, so that damage to the light emitting element 10 can be suppressed. Further, since the resin layer itself constituting the sealing layer 22 is not easily deteriorated by the plasma treatment, damage to the light emitting element 10 can be suppressed.

Hereinafter, the present invention will be described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

First, the materials used in the following examples are shown.
(A) UV curable resin 1: dimethylol-tricyclodecanediacrylate, light acrylate DCP-A, manufactured by Kyoeisha Chemical Co., Ltd. (A) UV curable resin 2: trimethylol propantriacrylate, light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd. (A) UV curable resin 3: neopentyl glycol diacrylate, light acrylate NP-A, manufactured by Kyoeisha Chemical Co., Ltd. (A) UV curable resin 4: 1.9-nonanediol diacrylate, light acrylate 1,9ND-A, Kyoeisha Chemical Co., Ltd. (A) UV curable resin 5: lauryl acrylate, light acrylate LA, Kyoeisha Chemical Co., Ltd. (B) UV radical initiator 1: 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, Omnirad TPO H, IGM Resins (C) Antioxidant 1: Dibutylhydroxytoluene, BHT, Tokyo Kasei Kogyo Co., Ltd. (C) Antioxidant 2: Pentaerythritol Tetrakiss [3- (3,5-di-tbutyl-4-hydroxy) Phenyl) propionate, AO-60, manufactured by ADEKA (D) Polymeric initiator: 4-Hydroxy-2,2,6,6-tetramethylpiperidine 1-Oxyl Free Radical, manufactured by Tokyo Kasei Kogyo Co., Ltd.

(Examples 1 to 10, Comparative Examples 1 to 11)
Each component was blended so as to have the blending composition shown in Table 1 or Table 2, and a liquid curable composition was obtained as a sealing agent.
The physical characteristics of the encapsulant or the cured product thereof obtained in each example were measured by the following methods. The measurement results are also shown in Tables 1 and 2.

(Glass-transition temperature)
The cured product of the encapsulant obtained in each example was obtained by the following procedure. That is, using a 100 μm thick Teflon (registered trademark) sheet as a mold, an uncured encapsulant is sandwiched between PET films, and a UV-LED with a wavelength of 395 nm has an illuminance of 1000 mW / cm ² and an integrated light intensity of 1500 mJ / cm ² . It was cured under the conditions to obtain a cured product.
The obtained cured product was cut into a size of 10 mm in width × 40 mm in length with a cutter.
Then, using the dynamic viscoelasticity measuring device "DMS6100" (manufactured by Seiko Instruments Inc.), the cured product cut out in the atmosphere is heated at a temperature of 5 ° C./min from room temperature to 250 ° C. while applying a frequency of 1 Hz. , Tan δ was measured, and the temperature of the peak top of tan δ was taken as Tg of the cured product.
Those having a Tg of 90 ° C. or higher and lower than 200 ° C. were evaluated as acceptable (◯), and those having a Tg of less than 90 ° C. or 200 ° C. or higher were evaluated as rejected (×).

(viscosity)
The viscosity of the curable composition obtained in each example was measured at 25 ° C. and 20 rpm using an E-type viscometer (LV DV-II + Pro, manufactured by BROOKFIELD).

(Dielectric constant)
A coating film for obtaining a cured product for measuring the dielectric constant was prepared by the following method. That is, the obtained encapsulant was introduced into an inkjet cartridge DMC-11610 (manufactured by FUJIFILM Dimension). The inkjet cartridge was set in an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix), and after adjusting the ejection state, the thickness after curing was increased on a substrate on which aluminum was vapor-deposited to a thickness of 100 nm on non-alkali glass. It was applied in a size of 5 cm × 5 cm so as to be 10 μm.
The obtained coating film was placed in a box at room temperature (25 ° C.) for 5 minutes to allow nitrogen to flow, and then irradiated with ultraviolet rays having a wavelength of 395 nm under the conditions of an illuminance of 1000 mW / cm ² and an integrated light intensity of 1500 mJ / cm ² , and cured. A film was formed.
Then, aluminum was deposited on the inkjet coated surface to a thickness of 100 nm, and the dielectric constant was measured with an LCR meter HP4284A (manufactured by Agilent Technologies) under the condition of 100 kHz by an automatic balanced bridge method.

(Evaluation methods)
The damage of the organic EL element in the plasma processing step was evaluated by the following method.
The encapsulant obtained in each example was introduced into an inkjet cartridge DMC-11610 (manufactured by FUJIFILM Dimension). The inkjet cartridge is set in the inkjet device DMP-2831 (manufactured by Fujifilm Dimatic), and after adjusting the ejection state, the glass substrate has a size of 15 mm × 15 mm so that the cured thickness is 10 μm. Applied.
The obtained coating film was placed in a box at room temperature (25 ° C.) for 5 minutes to allow nitrogen to flow, and then irradiated with ultraviolet rays having a wavelength of 395 nm at 1500 mW / cm ² for 1 second to form a cured film.

The sample on which the cured film was formed was plasma-treated for 1 minute under a pressure condition of 2500 W ICP power supply, 300 W RF power supply, DC bias 200 V, argon (Ar) flow rate 50 sccm, and 10 mtorr.
Then, an inorganic sealing layer (SiN _x film) having a film thickness of 100 nm was formed by an RF sputtering method using a SiN _x target.
On the other hand, an OLED element was vapor-deposited on a facing substrate and bonded to a substrate on which an inorganic sealing layer was formed to obtain an evaluation sample.

The reliability test of the sample obtained in each example was carried out under the condition of 85 ° C. Specifically, the emission area ratio (%) after storing the samples obtained in each example at 85 ° C. for 100 hours was determined by the following method. That is, the light emitting area was calculated in the initial state and after storage for 100 hours using Motic Images Plus software (manufactured by Shimadzu Rika Co., Ltd.), the light emitting area ratio was obtained, and the evaluation was made according to the following criteria. Those with ◎ and ○ were accepted.
⊚: 85% or more ○: 75% or more and less than 85% Δ: More than 50 to less than 75% ×: 50% or less

(Bending resistance)
The curable composition obtained in each example was introduced into an inkjet cartridge DMC-11610 (manufactured by FUJIFILM Dimatix). The inkjet cartridge is set in an inkjet device DMP-2831 (manufactured by Fujifilm Dimatix), and after adjusting the ejection state, the thickness after curing becomes 10 μm on a 6 cm × 6 cm PET film (25 μm, A31). As described above, it was applied in a size of 5 cm × 5 cm. The obtained coating film was placed in a box at room temperature (25 ° C.) for 5 minutes to allow nitrogen to flow, and then irradiated with ultraviolet rays having a wavelength of 395 nm at 1500 mW / cm ² for 1 second to form a cured film.
The obtained cured film was used as a measurement sample to evaluate the bending resistance. With a bending tester (DML HP, manufactured by Yuasa System), set the bending radius to 1 mm, fix the measurement sample with double-sided tape (Nystack NW-15, manufactured by Nichiban), and 30 times per minute. A bending test was performed 300,000 times at a bending speed. The appearance was visually confirmed within 10 minutes after the completion of the bending 300,000 times, and the presence or absence of cloudiness was evaluated.
The evaluation criteria are shown below. Those with ◎ and 〇 were accepted.
◎: No white turbidity 〇: No breakage, but white turbidity ×: Breakage

From Tables 1 and 2, the encapsulants obtained in each example were excellent in the effect of suppressing damage to the organic EL element against plasma irradiation and also in excellent bending resistance.

This application claims priority on the basis of Japanese Application Japanese Patent Application No. 2020-1576559 filed on September 18, 2020, and incorporates all of its disclosures herein.

10 Light emitting element 21 Barrier layer, touch panel layer or surface protection layer 22 Sealing layer, overcoat layer, or barrier layer 23 Flattening layer or sealing layer 24 Barrier layer 50 Base material layer 100 Display device

Claims (7)

1. The following components (A) to (C):
   A sealant for a display device containing (A) a polymerizable compound (B) a polymerization initiator (C) an antioxidant.
   A sealant for a display element, wherein the glass transition temperature of the cured product of the sealant for the display element is 90 ° C. or higher and lower than 200 ° C.
2. The sealant for a display element according to claim 1, wherein the component (C) is a hindered phenol compound.
3. The first or second claim, wherein the component (C) is at least one of dibutylhydroxytoluene and pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]. Sealant for display elements.
4. The sealant for a display element according to any one of claims 1 to 3, wherein the component (A) is a compound containing a (meth) acryloyl group.
5. The sealing agent for a display element according to any one of claims 1 to 4, which is used for sealing an organic EL display element.
6. A cured product obtained by curing the sealant for a display element according to any one of claims 1 to 5.
7. With the board
   Display elements arranged on the substrate and
   The sealing layer that covers the display element and
   Including
   A display device in which the sealing layer is made of a cured product of the sealing agent for a display element according to any one of claims 1 to 5.

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